Digital camera modules are currently being incorporated into a variety of electronic devices. Such camera hosting devices include, but are not limited to, cellular telephones, personal data assistants (PDAs), and computers. The demand for digital camera modules continues to grow as the ability to incorporate the camera modules into host devices expands. Therefore, one design goal of digital camera modules is to make them as small as possible so that they will fit into an electronic device without substantially increasing the overall size of the device. Means for achieving this goal must, of course, preserve the quality of the image captured by the camera modules.
Such digital camera modules typically include a substrate, an image capture device, a housing, and a lens unit. The substrate is typically a printed circuit board (PCB) that includes circuitry to facilitate data exchange between the image capture device and the host device. The image capture device is mounted and electrically coupled to the circuitry of the PCB. The housing is then mounted on the PCB over the image capture device. The housing includes an opening that receives and centers the lens unit with respect to the image capture device. Typically, the opening includes a set of threads and the lens unit includes a complementary set of threads that facilitate the factory focusing of the camera module. During a factory focus operation, for example, focusing equipment rotates the lens unit with respect to the housing, which adjusts the distance between the lens unit and the image capture device. When the lens unit is properly focused, it is fixed in position with respect to the housing with an adhesive, a thermal weld, or the like. The housing also includes some type of ventilation opening so as to prevent a pressure differential between the inside and outside of the camera module that could otherwise damage sensitive camera module components (i.e., image capture device, lenses, filters, etc.). Ventilation is especially important during manufacturing processes when the camera module components are exposed to drastic temperature changes.
Although an opening is often necessary for ventilation, it also leads to problems. For example, particulate matter (e.g., dust, debris, etc.) can infiltrate the camera module through the opening. Of course, it is well known that when such matter contaminates a camera module, it substantially degrades image quality. During the manufacturing of camera modules, the internal components are especially vulnerable to contamination. Typically, contaminated camera modules are discarded, which can be expensive when yield losses are high. Minimizing such contamination typically requires expensive manufacturing processes that are carried out in special clean rooms. Even so, it is still difficult to prevent such contamination. Camera modules are also vulnerable to contamination after they are incorporated into host devices.
In an effort to reduce such contamination, some camera module manufacturers have reduced the size of the ventialation opening. However, size reduction is constrained by current tooling limitations and moding capabilities. Currently, the openings are approximately 0.03˜0.05 mm×0.15 mm.
What is needed, therefore, is a design for a camera module that includes air ventilation through which debris cannot pass. What is also needed is a design for a camera module that can be manufactured more easily and at higher success rate. What is also needed is a design for a camera module that has improved image quality.
It is against this background that a novel camera module design has been developed.